Thermoresponsive circuit controller



sumT/onnL 2 Sheets-Sheet l J. A. BREYMAIER THERMORESPONSIVE CIRCUIT CONTROLLER Filed Feb. 11, 1942 INSULA T/ON Jan. '5, 1943.

Inventor 2 Jacob A. Bregmaier;

His Attorney.

Jan. 5, 1943. .1. A. BREYMAIER THERMORESPONSIVE CIRCUIT CONTROLLER Filed Feb. 11, 1942 2 Sheets-Sheet 2 mm mm Fig. 5.

! ,INSULA TION Inventor. Jacob A. Bregmaier, b JV EJ His Afitorney.

Patented Jan. 5, 1943 :rnsamoansronsrvc cmomr con'mouna Jacob A. Breymaier, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application February 11, 1942, Serial No. 430,416

13 Claims. (01. 200-113) My invention relates to thermoresponsive circuit controllers and particularly to hot wire relays of the type having contacts normally biased toward circuit-closing position. Certain of the broader aspects of this invention are claimed in a copending application of George M. Hausler, Serial No. 430,770, filed February 13, 1942, and assigned to the same assignee as the instant application.

Hot wire relays of the normally open type ordinarily comprise a movable contact mounted upon a resilient member which is normally biased to bring the movable contact into engagement with a fixed contact, in combination with a thermally expansible member arranged to exert a tensile force upon the resilient member and to hold the contacts separated in the deenergized or contracted position of the expansible member. With such an arrangement the expansible memher is constantly under tension and, if it is broken for any reason, it will permit the contacts to engage and remain engaged so that other apparatus may become overloaded. It will be immediately evident that it is highly desirable to arrange a relay so that upon mechanical failure of the tensioned expansible member the contacts will assume an open rather than a closed position. By a normally open relay I mean one which is in a circuit opening position when deenergized.

Accordingly, it is an object of my invention to .provide a new and improved thermoresponsive circuit controller which shall assume a circuitopening position upon failure of the thermoresponsive member.

It is a further object of my invention to provide a normally open hot wire relay biased to a circuit-closing position and arranged to assume a circuit-opening position upon mechanical failure of the hot wire.

It is a still further object of my invention to' ing two spaced extreme positions in which the circuitecontrolling contacts are separated and an intermediate position in which the contacts are closed. The movable member is biased to one extreme position and is drawn-away from this position against its bias by the expansible wire under tension. In normal operation the expansion and contraction of the wire permits the movable member to move between its other extreme circuit-opening position and its intermediate position.

My invention itself will be better understood and its objects and advantages further appreciated by referring now to the following detailed specification taken in conjunction with the accompanying drawings in which Fig. 1 is a side view of a hot wire relay embodying my invention in one form; Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1; Fig. 3 is a plan view of a hot wire relay embodying my invention in a modified form; and Figs. 4 and 5 are plan and side views respectively of still another relay embodying my invention and characterized by snapacting operation.

Referring now to Figs. 1 and 2, I have shown a base In of suitable insulating material provided with an insulating supporting block ll, upon opposite sides of which are mounted a pair of separable contact springs l2 and l3. The contact springs l2 and 13 are biased inwardly into engagement with each other and carry at their free ends normally closed contacts I4. A support I5 extending upwardly from the base It] carries at its upper end a spool IE to provide a fixed support for one end of a thermally expansible wire I1. The lower end of the wire i1 is connected to an operating cam [8 of insulating material and the wire I1 is maintained under tension by means of a leaf spring I9 having one end fixed to the base"! and the other end in engagement with the lower portion of the operating cam la. The configuration of the operating cam l8 in a plane transverse to the contact springs l2 and i3 is such that the plate is wider at both ends than the space between the contact springs and tapers inwardly from both ends toward a reduced intermediate portion which is narrower than the space between the contact spring. Thus there is a, certain amount of lost motion between the contact springs l2 and I3 and the operating cam l8,

With the above understanding of the construction and arrangement of the various parts of the relay shown in Figs; 1 and 2 the mode of operation of the relay as a whole will be clear from the following brief description: In the position shown at Figs. 1 and 2, the wire .l! is cooled and contracted so that the operating cam I! is raised to its uppermost position against the bias of the spring I9 and. the tapered lower end portion of the block l8 engages and separates the contact springs l2 and I3. If anelectric current is passed through the expansible wire II or the wire is otherwise heated, the wire will increase in length and permit the spring l9 to draw the operating member l8 downwardly to an intermediate position in which the reduced center portion of the member I8 lies directly between the contact springs l2 and I 3- so that the member I8 is disengaged from both contact members l2 and i3. Under normal current and voltage conditions the cam I6 descends only to its intermediate position under high temperature conditions of the wire With the cam l8 in mid-position the contact springs l2 and I3 bring the contacts I 4 into engagement by virtue of their mutual inward bias. If now the expansible wire I1 is burned by excessive current or fails mechanically for some other reason the spring [9 will draw the cam l8 downwardly beyond its normal mid-position so that its tapered upper end portion engages and separates the contact springs I2 and I3.

. Referring now to Fig. 3, I have shown a modifled form of my invention embodied in a relay comprising a base 30 of suitable insulating material having mounted thereon a pair of resilient separable contact springs 3| and 32 and a resilient operating member 33. The contact springs 3| and 32 are mounted respectively at one end upon line terminal blocks 34 and 35 and carry at their free ends contacts 36 and 31, respectively. The springs 3| and 32 are mutually biased toward each other to bring the contacts 36 and 31 normally into engagement. A pair of fixed stops 38 and 39 are mounted upon the base 30 between the contact springs 3| and 32, respectively, to limit en, thereby permitting the actuating member 33 to move to the left under the influence of its own bias. Movement of the actuating member 33 to the left permits the contact spring 32 to move to the left in following engagement with the member 33 until the contact 31 comes into engagement with the contact '36. Continued expansion of the wire 44 and consequent continued movement of the actuating member 33 to the left after engagement of the contacts 36 and 31 will be taken up by the lost motion connection between the contact spring 32 and the resilient operating member 33. Normally such overtravel of the ac- 'tuating member 33 is insuflicient to bring the promoved sufliciently far to the left to engage the the contact closing movement of the contact springs 3| and 32.

The resilient actuating arm 33 is mounted at one end upon a supporting block 40 carried by the base I0 and is interconnected at its free end with the end of the'contact spring 32. The connection between the free end of the contact spring 32 and the free end of the actuating member 33 is arranged to provide a certain degree of lost motion between these elements and the actuating member 33 includes a projecting end portion 4| arranged to engage the free end of the contact spring 3|. The actuating member 33 is biased to the left, as viewed in the drawing, to a circuit opening position in which the projection 4| engages the contact spring 3| and holds the spring in a circuit opening position spaced from the stop 38. Intermediate its ends the actuating member 33 is provided with an attachment plate 42 of insulating material, anda similar attachment plate 43 is mounted upon the base 30. Between the plates 42 and 43 are strung any desired number of lengths of a thermally expansible wire 44.

In operation the relay of Fig. 3 functions in the following manner: In the position of the parts shown at Fig. 3 the expansible wire 44 is cooled and contracted so that the resilient actuating member 33 is drawn to its extreme righthand position, as viewed in the drawing, against its own bias. In this position, the actuating member 33 engages the free end of the contact spring 32 and draws the contact 31 out of engagement with the contact 36 against the biasof the contact spring 32. If now the expansible wire 44 is heated by the passage there'through of an electric current, or by any other suitable heating means, the wire will expand and lengthjection 4| of the actuating member into engagement with the free end of the contact spring 3|. If now the hot wire 44 fails mechanically for any reason, such as melting due to the passage of an excessive current, the spring members 3|, 32 and 33 are free to move under their own respective biases. Under these conditions the contact spring 32 will move to the left against the stop 39 and the resilient actuating member 33 will move to its extreme left-hand position to take up all thelost motion between its free end and the contact spring 32. In this position of the actuating member 33 the projection 4| has been contact spring 3| and move the contact 36 out of engagement with the contact 31.

Referring now to Figs. 4 and 5 I=have shown a snap acting hot wire relay embodying my invention in still another form. Referring to the drawings I have shown a base 50 of suitable insulating material having mounted thereon a pair of line terminal blocks 5|, 52 which serve to sup port cantilever contact springs 53 and 54, respectively, in parallel spaced relation. The spring 54 serves only as a wipe spring and carries at the end thereof a relatively stationary contact 55. Movement of the contact 55 in the circuit closing direction is limited by a stop 56 mounted upon the contact block 52. The contact spring 53 is longer than the contact spring 54 and carries at its free end a magnet keeper 51 for cooperation with a small permanent magnet 58 the function of which will be more fully explained hereinafter. Intermediate its ends and juxtaposed with respect to the fixed contact 55 the contact spring 53 carries a movablecontact 59. Movement of the contact spring 53 in a circuit closing direction is limited by a stop mounted upon the base 50 while its movement in a circuit opening direction is limited by a fixed stop 60a. In the unstressed position of both the contact springs 53 and 54 the contacts 55 and 59 are spaced from each other. The stops 56 and 60 are so disposed that the contact 59 may be.

brought into engagement with the contact 55 and is permitted a certain amount of overtravel against the bias of the wipe spring 54.

--Pivotally mounted upon a post 10 extending upwardly from the base 50 is a'bell crank lever having a longarm 1| extending in parallel spaced relation to the contact springs 53 and 54 and carry ing at its end the permanent magnet 56. A thermally expansible wire 13 is connected at its ends to two adjacent fixed studs 14 in the base 50 and is looped at approximately its center over a short arm 12 of the bell crank lever. It will of course be understood that it is not necessary to use a double wire 13, but that a single length of Wire between the arm 12 and a suitably located fixed anchorage will be suilicient and is contemplated within the scope of the invention. By means of a spring 15 the bell crank lever ll, 12 is biased in a counterclockwise direction, as viewed in Fig. 4, in order to hold the hot wire 13 constantly under tension.

In operation, the bell crank lever H, 12 of Figs. 4 and 5 is drawn against its bias to its extreme clockwise position, as viewed in Fig. 4, when the wire 13 is cooled and contracted. Upon the passage of current through the wire 13, or upon heating of the wire by any other desired means, the wire will expand and permit the spring -15 to move the bell crank lever ll, 12 in a counterclockwise direction, thereby to permit the permanent magnet 58 to approach the keeper 51. When the permanent magnet 58 reaches a predetermined position the keeper 51 is attracted thereto and the movable contact 59 is brought into engagement with the relatively stationary contact 55 with a snap action. Upon the reverse operation, when the thermally expansible wire 13 is cooled and contracted the Hell crank lever I I, I2 is moved in a clockwise direction, as viewed in Fig. 4, by the tensile force of the wire. As the permanent magnet 58 moves in this direction it carries with it the keeper 51 and stresses the contact spring 53 until the internal forces in the spring 53 are suificient to pull the keeper away from the magnet; At this time the contact 59 is separated from the contact 55 with a snap action and the parts assume their positions as shown at Fig. 4. In the event of fracture of the I hot wire 13 the bell crank lever H is moved to an extreme counterclockwise position by the biasing spring 15. This extreme counterclockwise position is beyond the normal contact closing position of the bell crank lever and is such that the permanent magnet 58 engages the keeper 5! and drives the contact spring 53 against the stop 60a positively to disengage the contact 59 from the contact 55 by bending the contact spring 53 in a counterclockwise direction as viewed in Fig. 4.

It will now be evident that I have provided a normally open hot wire relay so arranged that upon fracture of the thermal element the relaywill assume not a circuit-closing but rather a circuit-openingposition. For this purpose I have provided in a slow-acting form of relay a pair of contact members biased into engagement with each other in combination with an actuating member having two extreme positions in which it engages and separates the contact members and an intermediate position of disengagement with both contact members. The actuating member is biased to one of its extreme positions and is drawn away from this position by the tension of an expansible wire, the actuating member normally being movable between its inter mediate position and its opposite extreme position under the influence of the hot wire. In the snap acting form of my relay I provide a pair of spring-mounted contact members arranged to be spaced from each other in the unstressed positions of their mounting springs, in combination with an actuating member having two spaced extreme positions in one of which it engages one of the contact members positively to separate the contacts and in the other of which it has no influence whatever upon the contact members so that the contacts are separated of their own ac.- cord. When the operating member is in an intermediate position it magnetically attracts one of the contact members into engagement with the other. As in the other embodiments of my invention, the actuating member is biased to one of. its extreme contact separating positions and the influence of the hot wire.

While I have illustrated certain preferred embodiments of my invention by way of illustration many further modification will occur to those skilled in the art, and I therefore wish to have it understood that I intend by the appended claims to cover all such modifications as fall within the true spirit and scopeof my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A circuit controller comprising a pair of separable contact members biased into engagement with each other, operating means having two spaced contact separating positions and an intermediate position wherein said contacts are engaged, means for biasing said operating means to one of said contact separating positions, and thermally expansible means for controlling movement of said operating means, said thermally expansible means being arranged normally to prevent movement of said operating means into said one contact separating position.

2. A circuit controller comprising'a pair of point and the other end connected to said operating member thereby normally to prevent movement of said operating member into said first contact separating position and to control movement of said operating member between the other of said spaced contact separating positions and said intermediate position.

3. A circuit controller comprising a pair of separable contact members biased into engagement with each other, an operating member having. tw-o spaced positions of engagement with at least one of said contact members to separate said contact members and an intermediate position of disengagement from said contact memhere, means for biasing said operating member to one of said spaced contact separating positions, a thermally expansible tension member connected between said operating member and a fixed point'to hold said operating member in the other of said spaced contact separating positions against its bias when said tension member is cooled and contracted,.the expansion and contraction of said thermally expansible member under normal operating conditions being such that it controls movement of said operating member between said last-named contact separating position and said intermediate position while normally preventing movement of said operating member into said one contact separating posiis drawn away from this position by the tension treme positions'oi engagement with at least one of said contact members to separate said mem-. bers and an intermediate position of disengagement with both said contact members, means for biasing said operating member to one of said extreme positions, a thermally expansible wire under tension for retaining said operating member out of said one extreme position and controlling movements of said operating member between the other of said extreme positions and said intermediate position in response to changes in temperature of said wire.

5. A circuit controller comprising a pair of separable contact members biased into engagement with each other, a movable operating cam movable to engage at least one of said contact members thereby to separate said contact members, said cam having two spaced contact engaging portions and an intermediate portion spaced from said contact members, means for biasing said cam to a first position such that one of said contact engaging portions is operable to separate said contact members, a thermally expansible wire connected between said cam and a fixed point to hold said cam in a second position such that the other of said contact engaging portions is operable to separate said contact members when said wire is cooled and contracted, said wire being arranged when heated and elongated to permit said cam to take up an intermediate position out of engagement with both said contact members.

6. A circuit controller comprising a pair 01 separable contact members, an operating cam positioned between said contact members to separate said members, said cam having two tapered end portions arranged to engage and separate said contact members and a reduced intermediate portion joining said end portion, means for biasing said cam to a position such that one of said end portions engages said contact members, a thermally expansible wire connected between said cam and a fixed point to hold said cam in a second position such that the other of said end portions engages said contact members when said wire is cooled and contracted, said wire being arranged ,when heated and elongated to permitsaid cam to take up an intermediate position out of engagement with both said contact members.

- 7. A circuit controller comprising a pair of separable contact members biased into engagement with each other, stop means determining the engaging positions of each of said contact members, an operating member arranged separately to engage both said contact members and biased into engagement with one of said contact members to move said one contact member to a contact disengaging position, and thermally expansible means connected to move said operating member out of engagement with said one contact member and into engagement with the other of said contact members thereby to separate said contact members, said thermally expansible member being arranged when heated to take up a position of disengagement with both said contact members.

8. A circuit controller comprising a pair of separable contact members biased into engagement with each other, stop means determining the engaging positions of each of said contact memment with the other of said contact members, said operating member being biased to a position permitting said one contact member to assume its engaged position and being provided with a projection arranged to engage said other contact member and separate said members, and a thermally expansible wire connected between a fixed point and said operating member, said wire being arranged when cooled and contracted to move said operating member into engagement with said one contact member and when heated and elongated to permit said operating member to move to a position of disengagement with both said contact members.

9. A circuit controller comprising a pair of separable contact members, operating means continuously movable between two spaced contact separating position and having an intermediate position wherein said contacts are engaged, means for biasing said operating means to one of said contact separating positions, and thermally expansible means for controlling movement of said operating means, said thermally expansible means being arranged normally to prevent movement of said operating means into said one contact separating position.

and elongated to permit said operating member bers', an operating member having a lost motion connection with one of said contact members for 10. A circuit controller comprising a pair of separable contact members, operating means continuously movable between two spaced contact separating positions and having an intermediate position wherein said contacts are engaged, means for biasing said operating means to one of said contact separating positions, thermally expansible means under tension for controlling movement of said operating means to engage and sition when said thermally expansible member is heated and expanded, said thermally expansible member being arranged normally to prevent movement of said operating means into said one contact separating position, whereby said contact members are normally closed when said thermally expansible member is in its heated condition and are moved positively to a circuit opening position upon fracture of said thermally expansible member.

11. A circuit controller comprising a pair of resiliently mounted contact members biased to disengaging position, an operating member for said contact members having two spaced contact separating positions and an intermediate position in which said contacts are engaged, said operating member engaging at least one of said contact members when in one of said contact-separating positions positively to separate said contacts and being biased to said'one contact-separating position, thermally expansible means for normally moving said operating member between the other of said contact-separating positions and said intermediate position, said thermally expansible means being under constant tension to prevent said operating member from moving to said one contact separating position, and magnetic means controlled by said operating member to attract said contacts into engagement when said operating member is in said intermediate position. p

12. A circuit controller comprising a pair 01' contact springs disposed in parallel spaced relation,.a pair of switch contacts mounted upon said springs, said contacts being separated when said springs are unstressed, one of said contact springs extending beyond the other of said springs and carrying at its end a magnetic member, a movable operating lever carrying at its end a second magnetic member operable to attract said first magnetic member thereby to bring said switch contacts into engagement, said operating lever being biased into engagement with said one contact spring positively to separate said contact members, and a thermally expansible wire under tension for restraining said operating lever and controlling normal movement of said operating lever to bring said second magnetic member within and without the attractive range of said first 13. A circuit controller comprising a pair of circuit controlling contacts biased to a circuitclosing position, a thermally expansible tension member operatively associated with said contacts and arranged when cooled and contracted to restrain closing of said contacts, said tension member when heated and expanded permitting said contacts to move under the influence of their bias to said circuit-closing position, and spring means associated with said tension member for positively moving said contacts to a circuit-opening position upon fracture of said thermally ex- 

